Year current US$ 1995 25000000 1996 24000000 1997 23000000 1998 25000000 1999 30000000 2000 40000000 2001 88000000 2002 104000000 2003 128000000 2004 140000000 2005 148000000 2006 175000000 2007 221000000 2008 275000000 2009 192000000 2010 205000000 2011 210000000 2012 142000000 2013 178000000 2014 212000000 2015 186000000 2016 201000000 2017 206000000 2018 227000000